It is known to test hearing aid in a test box for quality control and/or for adjustment purposes.
In the test box, the sound output of the hearing aid to be tested is connected to a test microphone in a soundproof manner using an adaptor and a coupler such as a 2 cc coupler. One or more loudspeakers in the test box generate sound during the test for reception and processing by the hearing aid to be tested and the sound output by the hearing aid is guided towards test microphone in the test box. A reference microphone is positioned adjacent a microphone of the hearing aid to be tested in order to measure the actual level of the sound received by the hearing aid.
The test box is sound proof so that sound from the surroundings is prevented from interfering with the testing of the hearing aid.